As the denning phase comes to a close, we have been looking back at the last few months to develop a more complete picture of the interactions between Zhen Zhen and her mother. It can be hard, in the moment, to answer questions like: what is this cub like? And, what is Bai Yun doing differently? Although we can get a flavor of the situation inside the den, when we look at the data we have collected we can really see the differences and similarities between this year and our previous years with cubs born.
We have been saying all along that this cub is different from the others, more quiet. Our data indicates we were right on with that assessment. Zhen did not emit the highest level of vocalization, the “cry,” throughout the denning phase, except on one day (day 4). Cries were recorded for Gao Gao’s other offspring in the first three weeks of life, especially with Mei Sheng (boys!). And the next highest intensity vocalization, the “squawk,” occurred much less frequently with Zhen than her siblings throughout the entire denning phase, too (scroll to bottom of page to see graph). She seems to have been more content from birth, either as a factor of her personality or a function of Bai Yun’s excellent maternal care.
Bai Yun was different this time, too. She left the den regularly at an earlier time than with Zhen’s siblings. She spent more time feeding in the second month postpartum than with Gao Gao’s other cubs. She more readily placed Zhen in contact with the ground than with other cubs (see graph below). All of which suggests one of two things: either this cub was more tolerant and allowed her mother more freedom, or Bai Yun was more competent and more efficient at placating her infant so that she had more time to focus on her own needs.
In a sense, our research efforts have mirrored Bai Yun’s maternal efforts over the years. Initially, we looked at every clue and all evidence we could find to assess Bai Yun’s reproductive status during estrus and pregnancy. We sweated every detail when she gave birth to Hua Mei. With time, our success has allowed us to pare down and strip away the non-essential, and we can focus our energy and resources on those aspects of her behavior and biology we know are most informative to help us answer whatever questions and concerns we have. Likewise, Bai Yun no longer seems to waste time on prolonged estruses, extending courtship dances with Gao Gao, or fumbling with finding the best to calm a restless infant. She too has stripped away the non-essential and is extremely efficient at getting the job done, no matter what it may be.
I am curious about the long-term ramifications of this. Young Hua Mei has already proven to be a successful breeder and mother. Will Su Lin outshine her someday? Will Zhen be the ultimate in panda breeding success stories? Will Bai Yun’s grandchildren show different skill sets as a result of their mother’s different backgrounds? It’s hard to know where the legacy of good maternal care comes to an end, but it will be interesting to wait and see.
Suzanne Hall is a senior research technician with the San Diego Zoo’s Giant Panda Unit.
Scroll to the very bottom of this page to view Suzanne’s graphs.
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